Pipe grip



C. J. ESSELENG PIPE GRIP Filed Nov. 7, 1939 lill!!! Flegz v- Patented May 28,

v PIPE GRIP` l Cornelis iJ. Elaeling, Haarlem, Netherlands, alsigner to N. V. Gebr. Stork Cos Fabriek van Hijaehwerktuigen, Haarlem, Netherlands, a company oi the Netherlands Application; November 7, issn', serial No. soazcsf In the Netherlands November 29, 1938 This invention relates. to pipe grips used in rotary drilling. l

A rotary drilling lmachine comprises a horiz ontal table adapted, through a suitableclutch, to bedriven by a motor and provided with a pipe grip, which transmits rotary motion of the table to a drill pipe extending therethrough while perrnitting upward and downward movement of said.

pipe.

A n object of the invention is to provide a practical and desirable form of pipe grip. Other objects andthe novel features of construction, combinations and relations of parts by which the same are attained, will appear as the speciiicatio proceeds.

In the accompanying drawing, a preferred embodiment of the invention is illustrated, but it-is to be understood that the structure may be modified and changed as regards the present disclosure, within the true intent and broad scope of the invention.. l

Fig. 1 is a broken plan and part sectional view of the said embodiment, and

F18. 2 is a vertical sectional view ason line II1I, of Fig. i, some of thepartsbelng shownin elevation.

The illustrated grip comprises a iiat, horizontal support 3 `having holes 4 fitting vertical pins l! secured to the rotary table i. Said support is oi' annular formation and houses an annular cage l for three vertical rollers `1, which are spaced apart and radiallyvproject from said cage.

Mounted on .the top and the bottom side of support l are annular discs 8 .and 3, respectively, which partly project inwardly from the inner edge ofthe Support so asv to hold cage O in its vproper place.

Said discs are interconnected .by three vertical bolts Il, the 'central portion of each of which forms the pivot oi' a bracket II carrying two equally sized concave rollers I2, I2 projecting.

above disc l and below disc l, respectively. Said rollers are provided with circumferential corruga.

tions and rotatably mounted about'v parallel, horizontal axes lying in a common vertical plane, it being understood that the curvature of their concave generatrices is adapted to that of the drill pipe I3, which is to follow rotary motion imparted .to the table i through conventional means not shown.

At the end remote from its' pivot bolt II, each (ci. ass-z3) The cage 8' is provided with three radial lugs I5 overhanging disc I. Each of said lugs bears against one washer I6 4oi a coiled spring I1,'whose second washer I8 is adjustably mounted on a horizontal screw bolt I9, which is encircled by said springand hinged about a vertical stud.bolt

2l tappedv in disc 8. y

The grip described so far operates as follows:

'I'he springs I'Il tend to urge the chuck, formed by the discs 8, Sand the parts associated therewith, in a direction wherein the 4rollers 1 move up the inclines formed by the races I4.

Owing thereto, the grips formed by the brackets II yandv the rollers i2,- I2* rotatably mounted therein, swivel inwards yabout their` pivots I0 through very small angular distances, since the rollers 1 arepositlvely prevented from outward movement. Consequently, the rollers I2, I2* are `forcibly pressed against the drill pipe I 3, w'hich thus is coupled with the table 5 for rotation therewith, while retaining freedom of being fed through or withdrawn so as to cause the rollers I2, I2 to revolve about their axes. If so desired, the gravity of the drill pipe I2 may be reduced 'or increased by means of weights or the like., A

If, during drilling, the resistance encountered by the bit (not shown) secured to the lower end *of the drill string abruptly decreases by a considerable amount, the torque accumulated in the string is released, so that pipe I3 is Suddenly accelerated.I If said acceleration were allowed to be transmitted to base plate 3, dangerous strains would be set up in the driving gear or in the motor. This transmission is, however, obviated by the one-way clutch I, 1, Il, it being understood that, if drill pipe Il tendsl to rotate at a speed exceeding that .of the table 5 as a consequence of the torque therein, the rollers 'l will lag behind the chuck and the coupling is temporarily released- Thereafter, the yholding en? gagement is restored by the springs I1.

Since the drill pipe I3 will not always-assume a position exactly rectangular to the support 2,'i. e.,-

ment with said pipe.' .With ay view to obviating `this inconvenience, each bracket II is mounted forswinging motion about a horizontalaxis c'entrally between', and in parallel relation with the axes of their rollers I2, I2.. This freedom of swinging motion in a vertical plane passingy throughihe axis of pipe I3 is due to the fact that the central part I0* of each bolt I 0' is slightly barrel shaped and bracket II.

fits in a cylindrical hole of its What I claim is:

1. In combination with a rotary table, a support associated with said table to follow rotary movementthereof, a chuck rotatably mounted in said support and carrying a plurality of pipe grips each comprising, in addition to a bracket mounted for swinging motion about an axial axis, of at least one roller mounted in said bracket for rotation about a tangential axis, wedging means i'or causing said pipe grips to swing abouty their axes into holding engagement with drill pipe extending through said table, and a spring element tending to bring about said wedging action.

2. In combination with a rotary table, a support associated with said table to follow rotary movement thereof, a chuck rotatably mounted in said support and carrying a plurality o! pipe grips each comprising, in addition ta a bracket mounted for swinging motion' about an axial axis, of at least two rollers mounted in said bracket for rotation about tangential axes, said Ibracket being also mounted for swinging movement about an axis parallel with and located intermediate the roller ax'es, wedging means for causing said pipe grips to swing about their axial axes into holding engagement with drill pipe extending through said table,` and a spring element tending to bring about said wedging action. 

